It will be the first animated feature ever to open the Cannes film festival this year, and is produced by a company whose last two films won the best animation Oscar. Yet Pixar's next project, Up, is now the target of Wall Street analysts and toy manufacturers alike, for not being commercial enough.

Up, which will be released in UK cinemas in October, certainly is not the standard Pixar fare. Rather than being populated with flying Space Rangers or anthropomorphic motorcars, it tells the tale of a septuagenarian adventurer who attaches thousands of brightly coloured balloons to the roof of his home in order to fly to South America. According to the New York Times, this has sparked concerns among analysts that the movie will not be the computer-generated cash cow from Pixar, or indeed parent Walt Disney Company, to which they have become accustomed.

Doug Creutz of Wall Street firm Cowen and Company told the paper there was widespread concern that Pixar was on a downward spiral in commercial terms. "The worries keep coming despite Pixar's track record, because each film it delivers seems to be less commercial than the last," he said. Industry watcher Richard Greenfield of Pali Research, who advised clients to sell Disney shares last month, said: "We doubt younger boys will be that excited by the main character." Up has a budget of $175m (£120m) and took four years to make.

There are also concerns from toy-makers that Up will prove a downer. Thinkway Toys, whose range of products related to Pixar's 2006 film Cars helped the film to a merchandise sales record of $5bn, is not creating a single toy based on the new movie. Disney stores will offer only limited merchandise to promote Up.

Disney chief executive, Robert A Iger, said the company was focused on delivering "great films", rather than adopting a blind adherence to commercial pressures. "If a great film gives birth to a franchise, we are the first company to leverage such success," he said. "A check-the-boxes approach to creativity is more likely to result in blandness and failure."